Eruption and tsunami in Tonga: the shock wave recorded as far as France

The eruption of the volcano was heard as far as Alaska, and felt as far as France, 17,000 kilometers from Tonga, where meteorological measuring devices recorded the shock wave.

A shock wave felt 17,000 km away. The Tonga Islands suffered the eruption of the Hunga Tonga volcano on one of the country’s uninhabited islands on Saturday: a huge mushroom of smoke and ash, immediately followed by the outbreak of a wave was observed from space. The island nation has suffered significant damage, including being cut off from the world for at least two weeks according to New Zealand authorities, as an undersea communications cable was cut in the disaster.

Saturday’s eruption was so powerful it was heard as far away as Alaska, triggering a Pacific tsunami that flooded coasts from Japan to the United States, and killed two people in Peru. Traces of the earthquake were even felt on French weather monitoring devices.

The eruption heard as far as Alaska

Following the eruption, 1.2 meter waves swept over Tonga’s capital, where residents fled to higher ground, leaving behind flooded homes as rocks and ash fell from the sky . On site, the damage is currently difficult to assess due to the lack of communication.

But more than 10,000 kilometers away in Peru, two women drowned on Naylamp beach in Lambayeque, in the north, due to “abnormal waves” following the eruption in Tonga, the local National Emergency Operations Center announced on Sunday.

The eruption triggered tsunamis in the Pacific, with waves of 1.74 meters measured in Chanaral, Chile, and smaller observed along the Pacific coast from Alaska to Mexico. Waves of about 1.2 meters also hit Japan.

In California, the city of Santa Cruz was flooded by a tidal wave generated by the tsunami, according to videos shared by the US Weather Service. The American Geological Institute (USGS) has recorded the eruption as equivalent to a magnitude 5.8 earthquake at zero depth.

The eruption was also heard as far away as Alaska tweeted the Institute of Geophysics at the University of Alaska Fairbanks. “The very broad signal is not that surprising given the magnitude of the eruption, but the audible aspect is quite unique,” he points out.

Repercussions recorded in France

And the wave did not stop at the shores of the Pacific.

“Incredible and fascinating. In the middle of the evening, all Météo-Varoise weather stations have just recorded the sharp variations in atmospheric pressure following the shock wave from the eruption of the volcano in the Tonga Islands, which produced around 6:10 am French time this day”, wrote the Facebook account Météo Varoise on Saturday, adding that “many other weather stations in Western Europe have recorded these variations”.

Guillamue Séchet, weather specialist for BFMTV, noted on Twitter “two clearly visible pressure variations on our Paris Saint-Germain-des-Prés station”, Saturday evening. “An unusual event!”, he notes.

If these waves were recorded by measuring devices, they were not felt by the population. “At this distance, there is no risk of anything special physically”, explains Météo Varoise, taking the example of ricochets: “You throw a small stone and a large stone into a lake, in both cases you will have several waves which will propagate circularly, but not at the same intensity”.

“It’s very impressive, but you have to imagine that in 1883, the wave of the eruption of Krakatoa in Indonesia had circled the planet 7 times”, explains on The 1st Philipson Bani, volcanologist at the IRD (Research Institute for Development).

“A significant impact on the northern coastline of Nuku’alofa”

New Zealand sent a reconnaissance aircraft early Monday to Tonga for “an initial assessment of the impact on the low-lying area and islands”, but information is trickling in. Tonga has also accepted an Australian offer to send a surveillance plane, according to Canberra. Australia was preparing for its part “essential humanitarian commodities” to send.

“The tsunami had a significant impact on the northern coastline of Nuku’alofa”, the capital of Tonga, “with boats and large rocks washing up on the shore”, said New Zealand Prime Minister Jacinda Ardern. “Nuku’alofa is covered in a thick cloud of volcanic ash, but otherwise the situation is calm and stable,” she added after contacting her country’s embassy in Tonga. However, the archipelago needs to supply itself with water because “the ash cloud caused contamination“.

“Deeply concerned for the people of Tonga”, tweeted US Secretary of State Antony Blinken, “ready to send help”. World Health Organization chief Tedros Adhanom Ghebreyesus tweeted that the WHO was “ready to support the government and provide assistance”.

The United Nations children’s agency (UNICEF) was preparing emergency supplies for Tonga, in coordination with Australia and New Zealand.